This chapter would have been a real roller-coaster ride as we were taken into some internal depth of the PySide programming. We started with discussing event handlers and reimplementation techniques to achieve the task at hand. We also discussed about event filters and re-implementing the notify() function. Unless absolutely necessary the latter forms of re-implementing events should be avoided to make an efficient program.

We then explored the very fundamental mechanism to Qt, signals, and slots. The signals and slots mechanism follow an observer pattern listening and binding to objects when called. We started with implementing the built-in signals and slots. Later in this section, we implemented and emitted our own custom signals and also discussed how to listen to them.

In the latter half, we shifted our focus to diagrams and graphics. Starting with the drag-and-drop functionality usage, we have also seen various types of QPainter draw objects. The chapter ended with a brief discussion on graphics and effects. The examples that are shown in the latter half of the chapter are very basic examples to help you understand the basic concepts. Much more complex applications can be designed and it would by itself be a subject matter for a complete book.